Luminescence device, display apparatus and metal coordination compound

ABSTRACT

A luminescence device is principally constituted by a pair of electrodes and an organic compound layer disposed therebetween. The layer contains a metal coordination compound represented by the following formula (1):  
                 
 
     wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independently denote hydrogen atom or a substituent selected from the group consisting of halogen atom; nitro group; trifluoromethyl group trialkylsilyl group having three linear or branched alkyl groups each independently having 1-8 carbon atoms; and a linear or branched alkyl group having 2-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom; with the proviso that at least one of X1 to X8 is a substituent other than hydrogen atom, and X2 and X3 cannot be fluorine atom at the same time.

FIELD OF THE INVENTION AND RELATED ART

[0001] The present invention relates to a luminescence device, a metalcoordination compound therefor and a display apparatus including theluminescence device. More specifically, the present invention relates toan organic (electro-)luminescence device employing a metal coordinationcompound having a formula (1) or (2) appearing hereinafter as aluminescence material, the metal coordination compound adapted for usein the luminescence device, and a display apparatus using theluminescence device.

[0002] An organic electroluminescence (EL) device has been extensivelystudied as a luminescence device with a high responsiveness and highefficiency.

[0003] The organic EL device generally has a sectional structure asshown in FIG. 1A or 1B (e.g., as described in “Macromol. Symp.”, 125,pp. 1-48 (1997)).

[0004] Referring to the figures, the EL device generally has a structureincluding a transparent substrate 15, a transparent electrode 14disposed on the transparent substrate 15, a metal electrode 11 disposedopposite to the transparent electrode 14, and a plurality of organic(compound) layers disposed between the transparent electrode 14 and themetal electrode 11.

[0005] Referring to FIG. 1, the EL device in this embodiment has twoorganic layers including a luminescence layer 12 and a hole transportlayer 13.

[0006] The transparent electrode 14 may be formed of a film of ITO(indium tin oxide) having a larger work function to ensure a good holeinjection performance into the hole transport layer. On the other hand,the metal electrode 11 may be formed of a layer of aluminum, magnesium,alloys thereof, etc., having a smaller work function to ensure a goodelectron injection performance into the organic layer(s).

[0007] These (transparent and metal) electrodes 14 and 11 may be formedin a thickness of 50-200 nm.

[0008] The luminescence layer 12 may be formed of, e.g., aluminumquinolinol complex (representative example thereof may include Alq3described hereinafter) having an electron transporting characteristicand a luminescent characteristic. The hole transport layer 13 may beformed of, e.g., triphenyldiamine derivative (representative examplethereof may include α-NPD described hereinafter) having an electrondonating characteristic.

[0009] The above-described EL device exhibits a rectificationcharacteristic, so that when an electric field is applied between themetal electrode 11 as a cathode and the transparent electrode 14 as ananode, electrons are injected from the metal electrode 11 into theluminescence layer 12 and holes are injected from the transparentelectrodes 14.

[0010] The thus-injected holes and electrons are recombined within theluminescence layer 12 to produce excitons, thus causing luminescence. Atthat time, the hole transport layer 13 functions as an electron-blockinglayer to increase a recombination efficiency at the boundary between theluminescence layer 12 and the hole transport layer 13, thus enhancing aluminescence efficiency.

[0011] Referring to FIG. 1B, in addition to the layers shown in FIG. 1A,an electron transport layer 16 is disposed between the metal electrode11 and the luminescence layer 12, whereby an effective carrier blockingperformance can be ensured by separating functions of luminescence,electron transport and hole transport, thus allowing effectiveluminescence.

[0012] The electron transport layer 16 may be formed of, e.g.,oxadiazole derivatives.

[0013] In ordinary organic EL devices, fluorescence caused during atransition of luminescent center molecule from a singlet excited stateto a ground state is used as luminescence.

[0014] On the other hand, not the above fluorescence (luminescence) viasinglet exciton, phosphorescence (luminescence) via triplet exciton hasbeen studied for use in organic EL device as described in, e.g.,“Improved energy transfer in electrophosphorescent device” (D. F.O'Brien et al., Applied Physics Letters, Vol. 74, No. 3, pp. 442-444(1999)) and “Very high-efficiency green organic light-emitting devicesbased on electrophosphorescence” (M. A. Baldo et al., Applied PhysicsLetters, Vol. 75, No. 1, pp. 4-6 (1999)).

[0015] The EL devices shown in these documents may generally have asectional structure shown in FIG. 1C.

[0016] Referring to FIG. 1C, four organic layers including a holetransfer layer 13, a luminescence layer 12, an excitondiffusion-prevention layer 17, and an electron transport layer 16 aresuccessively formed in this order on the transparent electrode (anode)14.

[0017] In the above documents, higher efficiencies have been achieved byusing four organic layers including a hole transport layer 13 of α-NPD(shown below), an electron transport layer 16 of Alq3 (shown below), anexciton diffusion-prevention layer 17 of BPC (shown below), and aluminescence layer 12 of a mixture of CPB (shown below) as a hostmaterial with Ir(ppy)₃ (shown below) or PtOEP (shown below) as a guestphosphorescence material doped into CBP at a concentration of ca. 6 wt.%.

[0018] Alq3: tris(8-hydroxyquinoline) aluminum (aluminum-quinolinolcomplex),

[0019] α-NPD:N4,N4′-di-naphthalene-1-yl-N4,N4′-diphenyl-biphenyl-4,4′-diamine(4,41-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl),

[0020] CBP: 4,4′-N,N′-dicarbazole-biphenyl,

[0021] BCP: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline,

[0022] Ir(ppy)₃: fac tris(2-phenylpyridine)iridium(iridium-phenylpyridine complex), and

[0023] PtEOP: 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum(platinum-octaethyl porphine complex).

[0024] The phosphorescence (luminescence) material used in theluminescence layer 12 has attracted notice. This is because thephosphorescence material is expected to provide a higher luminescenceefficiency in principle.

[0025] More specifically, in the case of the phosphorescence material,excitons produced by recombination of carriers comprise singlet excitonsand triplet excitons presented in a ratio of 1:3. For this reason, whenfluorescence caused during the transition from the singlet excited stateto the ground state is utilized, a resultant luminescence efficiency is25% (as upper limit) based on all the produced excitons in principle.

[0026] On the other hand, in the case of utilizing phosphorescencecaused during transition from the triplet excited state, a resultantluminescence efficiency is expected to be at least three times that ofthe case of fluorescence in principle. In addition thereto, ifintersystem crossing from the singlet excited state (higher energylevel) to the triplet excited state is taken into consideration, theluminescence efficiency of phosphorescence can be expected to be 100%(four times that of fluorescence) in principle.

[0027] The use of phosphorescence based on transition from the tripletexcited state has also been proposed in, e.g., Japanese Laid-Open PatentApplication (JP-A) 11-329739, JP-A 11-256148 and JP-A 8-319482.

[0028] An iridium-phenylpyrimidine complex having a methyl substituenthas been described in “Preprint for the 61-th Academical Lecture of theApplied Physics Society of Japan”, the third volume, P.1117, 6p-ZH-1(2000) (“Document 1”). Further, an iridium-phenylpyrimidine complexhaving 4-, 5-fluorine substituents (herein, referred to as a “metalcoordination compound A” has been described in “Polymer Preprints”,41(1), pp. 770-771 (2000) (“Document 2”).

[0029] However, the above-mentioned organic EL devices utilizingphosphorescence have accompanied with a problem of luminescentdeterioration particularly in an energized state.

[0030] The reason for luminescent deterioration has not been clarifiedas yet but may be attributable to such a phenomenon that the life oftriplet exciton is generally longer than that of singlet exciton by atleast three digits, so that molecule is placed in a higher-energy statefor a long period to cause reaction with ambient substance, formation ofexciplex or excimer, change in minute molecular structure, structuralchange of ambient substance, etc.

[0031] Accordingly, the (electro)phosphorescence EL device is expectedto provide a higher luminescence efficiency as described above, whilethe EL device is required to suppress or minimize the luminescentdeterioration in energized state.

SUMMARY OF THE INVENTION

[0032] An object of the present invention is to provide a luminescencedevice capable of providing a high-efficiency luminescent state at ahigh brightness (or luminance) for a long period while minimizing thedeterioration in luminescence in energized state.

[0033] Herein, although evaluation criteria for “high efficiency” and“high brightness (luminance) for a long period” may vary depending onluminescent performances required for an objective luminescence device(EL device), for example, a luminescence efficiency of at least 1 cd/Wbased on an inputted current value may be evaluated as “highefficiency”. Further, a luminance half-life of, e.g., at least 500 hoursat the time of luminescence at an initial luminance of 100 cd/m² may beevaluated as “high brightness (luminance) for a long period” or asmaller luminance deterioration in energized state.

[0034] Another object of the present invention is to provide a metalcoordination compound as a material suitable for an organic layer forthe luminescence device.

[0035] According to the present invention, there is provided aluminescence device, comprising: an organic compound layer comprising ametal coordination compound represented by the following formula (1):

[0036] wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8independently denote hydrogen atom or a substituent selected from thegroup consisting of halogen atom; nitro group; trifluoromethyl group;trialkylsilyl group having three linear or branched alkyl groups eachindependently having 1-8 carbon atoms; and a linear or branched alkylgroup having 2-20 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S—,—CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogenatom which can be replaced with fluorine atom; with the proviso that atleast one of X1 to X8 is a substituent other than hydrogen atom, and X2and X3 cannot be fluorine atom at the same time.

[0037] According to the present invention, there is also provided ametal coordination compound, adapted for use in a luminescence device,represented by the following formula (1):

[0038] wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8independently denote hydrogen atom or a substituent selected from thegroup consisting of halogen atom; nitro group; trifluoromethyl grouptrialkylsilyl group having three linear or branched alkyl groups eachindependently having 1-8 carbon atoms; and a linear or branched alkylgroup having 2-20 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S—,—CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogenatom which can be replaced with fluorine atom; with the proviso that atleast one of X1 to X8 is a substituent other than hydrogen atom, and X2and X3 cannot be fluorine atom at the same time.

[0039] The present invention provides a luminescence device, comprising:an organic compound layer comprising a metal coordination compoundrepresented by the following formula (2):

[0040] wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes analkylene group having 2-4 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S— or —CO— and capable of including hydrogen atom which can bereplaced with a linear or branched alkyl group having 1-10 carbon atoms;and X1 and X2 independently denote hydrogen atom; halogen atom; nitrogroup; trialkylsilyl group having 1-8 carbon atoms; or a linear orbranched alkyl group having 1-20 carbon atoms capable of including oneor at least two non-neighboring methylene groups which can be replacedwith —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable ofincluding hydrogen atom which can be replaced with fluorine atom.

[0041] The present invention also provides a metal coordinationcompound, adapted for use in a luminescence device, represented by thefollowing formula (2):

[0042] wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes analkylene group having 2-4 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S—or —CO— and capable of including hydrogen atom which can bereplaced with a linear or branched alkyl group having 1-10 carbon atoms;and X1 and X2 independently denote hydrogen atom; halogen atom; nitrogroup; trialkylsilyl group having 1-8 carbon atoms; or a linear orbranched alkyl group having 1-20 carbon atoms capable of including oneor at least two non-neighboring methylene groups which can be replacedwith —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable ofincluding hydrogen atom which can be replaced with fluorine atom.

[0043] The present invention further provides a display apparatusincluding the above-mentioned luminescence device and drive means fordriving the luminescence device.

[0044] These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIGS. 1A, 1B and 1C are respectively a schematic sectional view ofa layer structure of a luminescence device.

[0046]FIG. 2 is a graph showing a relationship between a Hammett'ssubstitution constant a and a peak (maximum) emission wavelength λ_(PE).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] In the case where a luminescence layer for an organic EL deviceis formed of a carrier transporting host material and a phosphorescentguest material, a process of emission of light (phosphorescence) maygenerally involve the following steps:

[0048] (1) transport of electron and hole within a luminescence layer,

[0049] (2) formation of exciton of the host material,

[0050] (3) transmission of excited energy between host materialmolecules,

[0051] (4) transmission of excited energy from the host materialmolecule to the guest material molecule,

[0052] (5) formation of triplet exciton of the guest material, and

[0053] (6) emission of light (phosphorescence) caused during transitionfrom the triplet excited state to the ground state of the guestmaterial.

[0054] In the above steps, desired energy transmission and luminescencemay generally be caused based on various quenching and competition.

[0055] In order to improve a luminescence efficiency of the EL device, aluminescence center material per se is required to provide a higheryield of luminescence quantum. In addition thereto, an efficient energytransfer between host material molecules and/or between host materialmolecule and guest material molecule is also an important factor.

[0056] Further, the above-described luminescent deterioration inenergized state may presumably relate to the luminescent center materialper se or an environmental change thereof by its ambient molecularstructure.

[0057] For this reason, our research group has extensively investigatedan effect of use of various metal coordination compounds as theluminescent center material and as a result, has found that the metalcoordination compound represented by the above-mentioned formula (1) or(2) allows a high-efficiency luminescence with a high brightness(luminance) for a long period (i.e., a decreased luminescentdeterioration in energized state).

[0058] The metal coordination compound of formula (1) may preferablyhave substituents X1 to X8 in which at least two of X1 to X8 aresubstituents other than hydrogen atom. Further, in the formula (1), atleast one of X5 to X8 may preferably be a substituent other thanhydrogen atom and/or at least two of X1 to X4 may preferably besubstituents other than hydrogen atom.

[0059] The metal coordination compound represented by the formulas (1)causes phosphorescence (luminescence) and is assumed to have a lowestexcited state comprising a triplet excited state liable to causemetal-to-ligand charge transfer (MLCT* state). The phosphorescentemission of light (phosphorescence) is produced during the transitionfrom the MLCT* state to the ground state.

[0060] The metal coordination compound of formula (1) according to thepresent invention has been found to provide a higher phosphorescenceyield of 0.1-0.9 and a shorter phosphorescence life of 1-60 μsec.

[0061] A phosphorescence yield (P(m)) is obtained based on the followingequation:

P(m)/P(s)=(S(m)/S(s))×(A(s)/A(m)),

[0062] wherein P(m) represents a phosphorescence yield of an (unknown)objective luminescent material, P(s) represents a known (standard)phosphorescence yield of standard luminescent material (Ir(ppy)₃), S(m)represents an integrated intensity of (photo-)excited emission spectrumof the objective material, S(s) represents a known integrated intensityof the standard material, A(m) represents an absorption spectrum of anexcited light wavelength of the objective material, and A(s) representsa known absorption spectrum of the standard material.

[0063] The shorter phosphorescence life is necessary to provide aresultant EL device with a higher luminescence efficiency. This isbecause the longer phosphorescence life increases molecules placed intheir triplet excited state which is a waiting state forphosphorescence, thus lowering the resultant luminescence efficiencyparticularly at a higher current density.

[0064] Accordingly, the metal coordination compound of formula (1)according to the present invention is a suitable luminescent materialfor an EL device with a higher phosphorescence yield and a shorterphosphorescence life.

[0065] Further, we have found that it is possible to control an emissionwavelength of the metal coordination compound of formula (1) byappropriately modifying the substituents X1 to X8 thereof. In thisregard, as a result of our investigation on various phosphorescencemetal coordination compounds for a blue luminescence material requiredto have a peak (maximum) emission wavelength of at most 490 nm, we havefound that it is very effective to introduce at least one substituenthaving a Hammett's substituent constant of at least 0.2 into the metalcoordination compound of formula (1) in order to provide a shorter peakemission wavelength.

[0066] More specifically we investigated a relationship betweenHammett's substituent constants a of substituents X2, X3 and X4 withrespect to carbon atom connected to iridium of an iridium complex (metalcoordination compound) shown below and peak emission wavelengths λ_(PE)in toluene at 25° C.

[0067] With respect to the Hammett's substituent constant σ, a Hammett'ssubstituent constant σm for meta-position was used for the substituentsX2 and X4 and a Hammett's substituent constant op for para-position wasused for the substituent X3. When two or more substituents other thanhydrogen atom were present at X2 to X4, a sum of σm and σp was used as aHammett's substituent constant σ.

[0068] In the present invention, specific values of σm and σp describedon pages 96-103 (Table 1) of “Correlation between Structure andActivation of Drugs”, Chemical Region Extra Edition 122, issued byNanko-do (Japan) were used as those for X2 to X4. A part of σm and σpdescribed therein is shown in Table 1 below. TABLE 1 Substituent σp σm F0.06 0.34 Cl 0.23 0.37 CF₃ 0.54 0.43

[0069] For example, a metal coordination compound (Example Compound No.(121) appearing hereinafter, X2=F, X3=CF₃, X4=H) has a Hammett'ssubstituent constant σ=0.34+0.54=0.88. In a similar manner, Hammett'ssubstituent constants σ of several metal coordination compounds (Ex.Comp. Nos. (1), (32), (122) and (111) described later and the metalcoordination compound A described in the above-mentioned Document 2) arecalculated and shown in Table 2 below together with corresponding peakemission wavelength λ_(PE) in toluene at 25° C. The results of Table 2are also shown in FIG. 2. TABLE 2 Compound σ λ_(PE) (nm) Ex. Comp. No.(1) 0.06 522 Metal coordination 0.40 505 compound A Ex. Comp. No. (32)0.54 487 Ex. Comp. No. (122) 0.68 471 Ex. Comp. No. (121) 0.88 466 Ex.Comp. No. (111) 0.91 479

[0070] As apparent from Table 2 and FIG. 2, introduction ofsubstituent(s) having a larger Hammett's substituent constant is veryeffective to shorten the peak emission wavelength. Specifically, themetal coordination compound having the sum of peak emission wavelengthsof at least 0.41, particularly at least 0.50 is suitable as the blueluminescent material. A similar effect can be expected also for metalcoordination compounds other than the metal coordination compound offormula (1) of the present invention.

[0071] As described above, the metal coordination compound of formula(1) is a suitable luminescent material for the EL device.

[0072] Further, as shown in Examples appearing hereinafter, it has beensubstantiated that the metal coordination compound of formula (1) of thepresent invention has an excellent stability in a continuousenergization test.

[0073] This may be attributable to introduction of particularsubstituents (X1 to X8) allowing control of intermolecular interactionwith a host luminescent material (e.g., CBP described above) andsuppression of formation of associated exciton leading to thermalquenching, thus minimizing quenching to improve device characteristics.

[0074] In this regard, the methyl group of methyl-substitutediridium-phenylpyrimidine complex described in the above-mentionedDocument 1 has a smaller bulkiness than ethyl group and methoxy groupand a smaller electronic effect than halogen atom, trifluoromethyl groupand methoxy group. As a result, the effect of controlling intermolecularinteraction in the present invention cannot be expected.

[0075] Further, compared with 4-, 5-fluorine (substituted)iridium-phenylpyrimidine complex (metal coordination compound A)described in the above-mentioned Document 2, it has been substantiatedthat a luminescence device using the metal coordination compound offormula (1) according to the present invention has a higher durability,i.e., a higher luminance stability for a long period, shown in Examplesdescribed later.

[0076] Further, in the case of phosphorescent (luminescent) material,luminescent characteristics are largely affected by its molecularenvironment. On the other hand, principal characteristics of thefluorescent material are studied based on photoluminescence.

[0077] For this reason, results of photoluminescence of thephosphorescent material do not reflect luminescent characteristics ofthe resultant EL device in many cases since the luminescentcharacteristics in the case of the phosphorescent material depend on amagnitude of polarity of ambient host material molecules, ambienttemperature, presence state of the material (e.g., solid state or liquidstate, etc. Accordingly, different from the fluorescent material, it isgenerally difficult to expect the resultant EL characteristics for thephosphorescent material by simply removing a part of characteristicsfrom photoluminescence results.

[0078] Next, the metal coordination compound of formula (2) according tothe present invention will be described.

[0079] The metal coordination compound of formula (2) may preferablyhave hydrogen atom(s) as at least one of X1 and X2 in the formula (2).

[0080] Similarly as the metal coordination compound of formula (1), themetal coordination compound of formula (2) also causes phosphorescence(luminescence) and is assumed to have a lowest excited state comprisinga triplet excited state liable to cause metal-to-ligand charge transfer(MLCT* state). The phosphorescent emission of light (phosphorescence) isproduced during the transition from the MLCT* state to the ground state.

[0081] The metal coordination compound according to the presentinvention has been found to provide a higher phosphorescence yield of0.15−0.9 and a shorter phosphorescence life of 1-40 μsec, as a result ofa luminescence test based on photo-luminescence by photo-excitation.

[0082] The shorter phosphorescence life is necessary to provide aresultant EL device with a higher luminescence efficiency. This isbecause the longer phosphorescence life increases molecules placed intheir triplet excited state which is a waiting state forphosphorescence, thus lowering the resultant luminescence efficiencyparticularly at a higher current density.

[0083] Accordingly, the metal coordination compound of formula (2)according to the present invention is a suitable luminescent materialfor an EL device with a higher phosphorescence yield and a shorterphosphorescence life.

[0084] Further, by appropriately modifying the alkylene group Y and/orthe substituents X1 and X2, emission wavelength control can be expectedfor the resultant metal coordination compound of formula (2).

[0085] As described above, the metal coordination compound of formula(2) is a suitable luminescent material for the EL device.

[0086] Further, as shown in Examples appearing hereinafter, it has beensubstantiated that the metal coordination compound of formula (2) of thepresent invention has an excellent stability in a continuousenergization test.

[0087] This may be attributable to introduction of particular alkylenegroup and/or substituents (Y, X1, X2) allowing control of intermolecularinteraction with a host luminescent material (e.g., CBP described above)and suppression of formation of associated exciton leading to thermalquenching, thus minimizing quenching to improve device characteristics.

[0088] The luminescence device (EL) device according to the presentinvention employs the above-mentioned metal coordination compound in anorganic layer, particularly a luminescence layer.

[0089] Specifically, the luminescence device may preferably include theorganic layer comprising the metal coordination compound of formula (1)or formula (2) between a pair of oppositely disposed electrodescomprising a transparent electrode (anode) and a metal electrode(cathode) which are supplied with a voltage to cause luminescence, thusconstituting an electric-field luminescence device.

[0090] The liquid crystal of the present invention has a layer structureshown in FIGS. 1A to 1C as specifically described above.

[0091] By the use of the metal coordination compound of formula (1) orformula (2) of the present invention, the resultant luminescence devicehas a high luminescence efficiency as described above.

[0092] The luminescence device according to the present invention may beapplicable to devices required to allow energy saving and highluminance, such as those for display apparatus and illuminationapparatus, a light source for printers, and backlight (unit) for aliquid crystal display apparatus. Specifically, in the case of using theluminescence device of the present invention in the display apparatus,it is possible to provide a flat panel display apparatus capable ofexhibiting an excellent energy saving performance, a high visibility anda good lightweight property. With respect to the light source, itbecomes possible to replace a laser light source of laser beam printercurrently used widely with the luminescence device according to thepresent invention. Further, when the luminescence device of the presentinvention is arranged in independently addressable arrays as an exposuremeans for effecting desired exposure of light to a photosensitive drumfor forming an image, it becomes possible to considerably reducing thevolume (size) of image forming apparatus. With respect to theillumination apparatus and backlight (unit), the resultant apparatus(unit) using the luminescence device of the present invention isexpected to have an energy saving effect.

[0093] The metal coordination compound of formula (1) may generally besynthesized through the following reaction scheme.

[0094] (Iridium complex)

[0095] (Rhodium complex)

[0096] Rh complex may be synthesized in the same manner as in Ir complexshown above.

[0097] (Palladium complex)

[0098] Specific and non-exhaustive examples of the metal coordinationcompound of formula (1) may include those (Example Compound Nos. (1-1)to (1-180)) shown in Tables 3-8 wherein Ex. Comp. Nos. (1-1) to (1-180)are simply indicated as (1) to (180), respectively. TABLE 3 No. M n X₁X₂ X₃ X₄ X₅ X₆ X₇ X₈  (1) Ir 3 H H F H H H H H  (2) Ir 3 H F H H H H H H (3) Ir 3 H H Cl H H H H H  (4) Ir 3 H H F H H OCH₃ H H  (5) Ir 3 H H FH H H Br H  (6) Ir 3 H C₂H₅ H H H H H H  (7) Ir 3 H H NO₂ H H H H H  (8)Ir 3 H H NO₂ H H H CF₃ H  (9) Ir 3 H H NO₂ H H NO₂ H H (10) Ir 3 H H NO₂H H OC₁₁H₂₃ H H (11) Ir 3 H H C₃H₇ H H H H H (12) Ir 3 H C₂H₅ OCH₃ H H HH H (13) Ir 3 H H C₃H₇ H H OC₄H₉ H H (14) Ir 3 H C₂₀H₄₁ H H H H H H (15)Ir 3 H H OCH₃ H H H H H (16) Ir 3 H OCH₃ OCH₃ H H H H H (17) Ir 3 H HOCH(CH₃)₂ H H H H H (18) Ir 3 H H OC₅H₁₁ H H H H H (19) Ir 3 H H OC₁₆H₃₃H H H H H (20) Ir 3 H H OCH₃ H H OCH₃ H H (21) Ir 3 H H OCH(CH₃)₂ H HOCH₃ H H (22) Ir 3 H H OC₁₀H₂₁ H H NO₂ H H (23) Ir 3 H H OCH(CH₃)₂ H H HCF₃ H (24) Ir 3 H H SCH₃ H H H H H (25) Ir 3 H OCH₂CH═CH₂ H H H H H H(26) Ir 3 H H OCH₂C≡CCH₃ H H H H H (27) Ir 3 H H COCH₃ H H H H H (28) Ir3 H H COCH₃ H H NO₂ H H (29) Ir 3 H H COCH₃ H H H CF₃ H (30) Ir 3 H HCOCH₃ H H OCH₃ H H

[0099] TABLE 4 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (31) Ir 3 H H COC₉H₁₉ H HH H H (32) Ir 3 H H CF₃ H H H H H (33) Ir 3 H H CF₃ H H H CF₃ H (34) Ir3 H H CF₃ H H NO₂ H H (35) Ir 3 H H CF₃ H H OCH(CH₃)₂ H H (36) Ir 3 HC₃F₇ H H H H H H (37) Ir 3 H H OCF₃ H H H H H (38) Ir 3 H OCF₃ H H H H HH (39) Ir 3 H H OCF₃ H H NO₂ H H (40) Ir 3 H H OCF₃ H H H CF₃ H (41) Ir3 H H OCF₃ H H OCH₃ H H (42) Ir 3 H H OCH₂C₃F₇ H H H H H (43) Ir 3 HO(CH₂)₃C₂F₅ H H H H H H (44) Ir 3 H H O(CH₂)₃OCH₂C₂F₅ H H H H H (45) Ir3 H H COOC₂H₅ H H H H H (46) Ir 3 H OCOCH₃ H H H H H H (47) Ir 3 H HO(CH₂)₂C₃F₇ H H H C₅F₁₁ H (48) Ir 3 H H H H H OCH₃ H H (49) Ir 3 H H H HH H CF₃ H (50) Ir 3 H H H H H H NO₂ H (51) Ir 3 H H Si(CH₃)₃ H H H H H(52) Ir 3 H H Si(CH₃)₂C₄H₉ H H H H H (53) Ir 3 H Si(CH₃)₂C₈H₁₇ H H H H HH (54) Ir 3 H H Si(C₂H₅)₃ H H H H H (55) Ir 3 H H H H H Si(CH₃)₂C₈H₁₃ HH (56) Ir 3 H C₂H₅ OCH₃ H H OCH₃ H H (57) Ir 3 H F H F H OCH₃ H H (58)Ir 3 H F H F H OCH₃ CF₃ H (59) Ir 3 H H Si(CH₃)₃ H H H Br H (60) Ir 3 HSi(CH₃)₂C₇H₁₅ OCH₃ H H H H H

[0100] TABLE 5 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (61) Rh 3 H H F H H H H H(62) Rh 3 F F H H H H H H (63) Rh 3 H H F H H OCH₃ H H (64) Rh 3 H H NO₂H H H H H (65) Rh 3 H H NO₂ H H OC₈H₁₇ H H (66) Rh 3 H H C₂H₅ H H H H H(67) Rh 3 H C₂H₅ OCH₃ H H H H H (68) Rh 3 H C₁₂H₂₅ H H H H H H (69) Rh 3H C₃H₇ H H H OCH₃ H H (70) Rh 3 H H OCH(CH₃)₂ H H H H H (71) Rh 3 H HOC₁₅H₃₁ H H H H H (72) Rh 3 H H OC₆H₁₃ H H NO₂ H H (73) Rh 3 H H OCH₃ HH OCH₃ H H (74) Rh 3 H H OCH(CH₃)₂ H H H CF₃ H (75) Rh 3 H H OCH₂CH═CH₂H H H H H (76) Rh 3 H OC≡CC₄H₉ H H H H H H (77) Rh 3 H H SC₂H₅ H H H H H(78) Rh 3 H H SCH₃ H H OCH₃ H H (79) Rh 3 H SCH₃ SCH₃ H H H H H (80) Rh3 H H COCH₃ H H H H H (81) Rh 3 H H COCH₃ H H OCH₃ H H (82) Rh 3 H H CF₃H H H H H (83) Rh 3 H H CF₃ H H OCH(CH₃)₂ H H (84) Rh 3 H H OCF₃ H H HCF₃ H (85) Rh 3 H H OCH₂C₄F₉ H H H H H (86) Rh 3 H H O(CH₂)₆C₂F₅ H H H HH (87) Rh 3 H H H H H OCH₃ H H (88) Rh 3 H H Si(CH₃)₃ H H H H H (89) Rh3 H Si(CH₃)₂C₆H₁₃ H H H H H H (90) Rh 3 H Si(CH₃)₂C₇H₁₅ OCH₃ H H H H H

[0101] TABLE 6 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈  (91) Pd 2 H H F H H H HH  (92) Pd 2 H F H F H H H H  (93) Pd 2 H H F H H OC₇H₁₅ H H  (94) Pd 2H H NO₂ H H H H H  (95) Pd 2 H H NO₂ H H OC₅H₁₁ H H  (96) Pd 2 H C₂H₅OCH₃ H H H H H  (97) Pd 2 H H C₅H₁₁ H H OCH₃ H H  (98) Pd 2 H C₁₅H₃₁ H HH H H H  (99) Pd 2 H H OCH(CH₃)₂ H H H H H (100) Pd 2 H H OC₃H₇ H H H HH (101) Pd 2 H H COC₈H₁₇ H H H H H (102) Pd 2 H H CF₃ H H H H H (103) Pd2 H H CF₃ H H OCH(CH₃)₂ H H (104) Pd 2 H H OCF₃ H H H CF3 H (105) Pd 2 HH Si(CH₃)₃ H H H H H (106) Pd 2 H H F H H OC₅H₁₁ H H (107) Pd 2 H H NO₂H H OC₃H₇ H H (108) Pd 2 H H C₂H₅ H H OCH₃ H H (109) Pd 2 H C₁₀H₂₁ H H HH H H (110) Pd 2 H H COCH₃ H H H H H (111) Ir 3 H Cl CF₃ H H H H H (112)Ir 3 H Cl CF₃ H H H CF3 H (113) Ir 3 H Cl CF₃ H H OCH3 H H (114) Rh 3 HCl CF₃ H H H H H (115) Rh 3 H Cl CF₃ H H H CF3 H (116) Rh 3 H Cl CF₃ H HCF3 H H (117) Rh 3 H Cl CF₃ H H OCH3 H H (118) Rh 3 H Cl CF₃ H H C₂H₅ HH (119) Pd 2 H Cl CF₃ H H H H H (120) Pd 2 H Cl CF₃ H H H CF3 CF3

[0102] TABLE 7 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (121) Ir 3 H F CF₃ H H HH H (122) Ir 3 H F H F H H H H (123) Ir 3 H CF₃ H CF₃ H H H H (124) Ir 3H CF₃ H F H H H H (125) Ir 3 H CF₃ CF₃ H H H Br H (126) Ir 3 F C₂H₅ H HH H H H (127) Ir 3 F H NO₂ H H H H H (128) Ir 3 F H NO₂ F H H CF₃ H(129) Ir 3 F H NO₂ H H NO₂ H H (130) Ir 3 F H NO₂ H H OC₁₁H₂₃ H H (131)Ir 3 F H C₃H₇ H H H H H (132) Ir 3 F C₂H₅ OCH₃ H H H H H (133) Ir 4 F HC₃H₇ H H OC₄H₉ H H (134) Ir 3 H C₂₀H₄₁ H F H H H H (135) Ir 3 H H OCH₃ FH H H H (136) Ir 3 H OCH₃ OCH₃ F H H H H (137) Ir 3 H H OCH(CH₃)₂ F H HH H (138) Ir 3 H H OC₅H₁₁ F H H H H (139) Ir 3 H H OC₁₆H₃₃ F H H H H(140) Ir 3 H H OCH₃ F H OCH₃ H H (141) Ir 3 H H OCH(CH₃)₂ H F OCH₃ H H(142) Ir 3 H H OC₁₀H₂₁ H F NO₂ H H (143) Ir 3 H H OCH(CH₃)₂ H F H CF₃ H(144) Ir 3 H H SCH₃ H C₂H₅ H H H (145) Ir 3 H OCH₂CH═CH₂ H H C₂H₅ H H H(146) Ir 3 H H OCH₂C≡CCH₃ H H H H F (147) Ir 3 H H COCH₃ H H H H F (148)Ir 3 H H COCH₃ H H NO₂ H F (149) Ir 3 H H COCH₃ H H H CF₃ F (150) Ir 3CF₃ H COCH₃ H H OCH₃ H H

[0103] TABLE 8 No. M n X₁ X₂ X₃ X₄ X₅ X₆ X₇ X₈ (151) Ir 3 F H COC₉H₁₉ HH H H H (152) Ir 3 H CF₃ H F H H H H (153) Ir 3 F H CF₃ H H H CF₃ H(154) Ir 3 H H CF₃ F H NO₂ H H (155) Ir 3 H H CF₃ F H OCH(CH)₂ H H (156)Ir 3 H C₃F₇ H CF₃ H H H H (157) Ir 3 H H OCF₃ H CF₃ H H H (158) Ir 3 HOCF₃ H H C₂H₅ H H H (159) Ir 3 H CF₃ H CF₃ H H H H (160) Ir 3 H H OCF₃ HF H CF₃ H (161) Ir 3 H H OCF₃ H H OCH₃ H F (162) Ir 3 H H OCH₂C₃F₇ H H HH F (163) Ir 3 H O(CH₂)₃C₂F₅ H H H H H F (164) Ir 3 H H O(CH₂)₃OCH₂C₂F₅Cl H H H H (165) Ir 3 H H COOC₂H₅ F H H H H (166) Rh 3 H OCOCH₃ H H F HH H (167) Rh 3 H H O(CH₂)₂C₃F₇ H C₂H₅ H C₅F₁₁ H (168) Rh 3 H H H H HOCH₃ H F (169) Rh 3 H H H H H H CF₃ F (170) Rh 3 H H H H H H NO₂ F (171)Rh 3 H H Si(CH₃)₃ H H H H F (172) Rh 3 H H Si(CH₃)₂C₄H₉ H H H H F (173)Rh 3 H Si(CH₃)C₈H₁₇ H F H H H H (174) Rh 3 H H Si(C₂H₅)₃ F H H H H (175)Rh 3 H H H F H Si(CH₃)C₆H₁₃ H H (176) Pd 2 H C₂H₅ OCH₃ F H OCH₃ H H(177) Pd 2 F H F F H OCH₃ H H (178) Pd 2 F H F F H OCH₃ CF₃ H (179) Pd 2F H Si(CH₃)₃ H H H Br H (180) Pd 2 F Si(CH₃)₂C₇H₁₅ OCH₃ H H H H H

[0104] The metal coordination compound of formula (2) may generally besynthesized through the following reaction scheme.

[0105] (Iridium complex)

[0106] (Rhodium complex)

[0107] Rh complex may be synthesized in the same manner as in Ir complexshown above.

[0108] (Palladium complex)

[0109] Specific and non-exhaustive examples of the metal coordinationcompound of formula (2) may include those (Example Compound Nos. (2-1)to (2-200) shown in Tables 9-15 wherein Ex. Comp. Nos. (2-1) to (2-200)are simply indicated as (1) to (200), respectively.

[0110] In Tables 9-15, symbols A to C′ for alkylene group Y representsalkylene groups shown below.

[0111] A: —CH₂CH₂—

[0112] D: —CH₂OCH₂—

TABLE 9 No M n Y R₁ R₂ X₁ X₂  (1) Ir 3 A — — H H  (2) Ir 3 A — — OCH₃ H (3) Ir 3 B H — H H  (4) Ir 3 B H — OCH₃ H  (5) Ir 3 B H — H CF₃  (6) Ir3 B H — H Cl  (7) Ir 3 B CH₃ — H H  (8) Ir 3 B CH₃ — F H  (9) Ir 3 B CH₃— NO₂ H (10) Ir 3 B C₂H₅ — H H (11) Ir 3 B C₃H₇ — H CF₃ (12) Ir 3 BC₂H₅(CH₃)CHCH₂ — H H (13) Ir 4 B C₆H₁₃ — OCH(CH₃)₂ H (14) Ir 3 B C₁₀H₂₁— Si(CH₃)₃ H (15) Ir 3 C H H H H (16) Ir 3 C H H OCH₃ H (17) Ir 3 C H HH CF₃ (18) Ir 3 C H H F H (19) Ir 3 C H H NO₂ H (20) Ir 3 C H H OC₅H₁₁ H(21) Ir 3 C H H O(CH₂)₂C₃F₇ H (22) Ir 3 C H H H Si(C₂H₅)₃ (23) Ir 3 C HH H Br (24) Ir 3 C H H CH₃ H (25) Ir 3 C CH₃ H CH₃ H (26) Ir 3 C H CH₃ HH (27) Ir 3 C CH₃ CH₃ H H (28) Ir 3 C C₃H₇ H Si(CH₃)₃ H (29) Ir 3 C HC₅H₁₁ H H (30) Ir 3 C C₈H₁₇ H Cl H

[0113] TABLE 10 No M n Y R₁ R₂ X₁ X₂ (31) Ir 3 C C₂H₅ C₂H₅ H C₇F₁₅ (32)Ir 3 C H C₆H₁₃ NO₂ H (33) Ir 3 C C₁₀H₂₁ H CF₃ H (34) Ir 3 C H C₉H₁₉ HOC₄H₉ (35) Ir 3 D — — H H (36) Ir 3 D — — OCH₃ H (37) Ir 3 E H — H H(38) Ir 3 E H — H NO₂ (39) Ir 3 E CH₃ — H H (40) Ir 3 E CH₃ — OCH₃ H(41) Ir 3 E CH₃ — H CF₃ (42) Ir 3 E CH₃ — NO₂ H (43) Ir 3 E CH₃ — OC₃H₇H (44) Ir 3 E C₂H₅ — H H (45) Ir 3 E C₂H₅ — H CF₃ (46) Ir 3 E C₃H₇ — H H(47) Ir 3 E C₃H₇ — OC₅H₁₁ H (48) Ir 3 E (CH₃)₂CHCH₂CH₂ — H H (49) Ir 3 EC₅H₁₁ — H C₄F₉ (50) Ir 3 E C₆H₁₃ — H H (51) Ir 3 E C₆H₁₃ — H Br (52) Ir3 E C₆H₁₃ — NO₂ H (53) Ir 3 E C₈H₁₇ — H H (54) Ir 3 E C₉H₁₉ — OCH₂C≡CCH₃H (55) Ir 3 E C₁₀H₂₁ — H H (56) Ir 3 E C₁₀H₂₁ — OCH₂CH═CH₂ H (57) Ir 3 FH — OCH₃ H (58) Ir 3 F CH₃ — H H (59) Ir 3 F CH₃ — OCH₃ H (60) Ir 3 FC₂H₅ — H CF₃

[0114] TABLE 11 No M n Y R₁ R₂ X₁ X₂ (61) Ir 3 F C₆H₁₃ — OCH(CH₃)₂ H(62) Ir 3 F C₈H₁₇ — Si(CH₃)₂C₈H₁₇ H (63) Ir 3 G H — OCH₃ H (64) Ir 3 G H— H CF₃ (65) Ir 3 G H — O(CH₂)₃OCH₂C₂F₅ H (66) Ir 3 G CH₃ — H H (67) Ir3 H H H H H (68) Ir 3 H CH₃ H Si(CH₃)₃ H (69) Ir 3 H H CH₃ H Cl (70) Ir3 I H H H H (71) Ir 3 I H H OCH₃ H (72) Ir 3 I H H H CF₃ (73) Ir 3 I H HH CH₃ (74) Ir 3 I C₂H₅ H COOC₂H₅ H (75) Ir 3 I H C₅H₁₁ OCH₂CH═CH₂ H (76)Ir 3 J H — H H (77) Ir 3 J H — NO₂ H (78) Ir 3 J CH₃ — OCH₃ H (79) Ir 3K H — H H (80) Ir 3 K H — H Si(CH₃)₃ (81) Ir 3 K C₃H₇ — H CF₃ (82) Ir 3L H H H H (83) Ir 3 L CH₃ H SC₂H₅ H (84) Ir 3 L H CH₃ OC₆H₁₃ H (85) Ir 3M H H H H (86) Ir 3 M C₂H₅ H COOC₃H₇ H (87) Ir 3 M H C₂H₅ H O(CH₂)₃C₂F₅(88) Ir 3 N — H H H (89) Ir 3 N — C₂H₅ H NO₂ (90) Ir 3 N — C₆H₁₃ Cl H

[0115] TABLE 12 No M n Y R₁ R₂ X₁ X₂  (91) Ir 3 O H — H H  (92) Ir 3 O H— H Si(C₂H₅)₃  (93) Ir 3 O C₈H₁₇ — OCH(CH₃)₂ H  (94) Ir 3 P H — H H (95) Ir 3 P C₃H₇ — H COOCH₃  (96) Ir 3 P C₆H₁₃ — H H  (97) Ir 3 Q H — HH  (98) Ir 3 Q C₄H₉ — O(CH₂)₃CH═CH₂ H  (99) Ir 3 R — — H H (100) Ir 3 R— — H CF₃ (101) Ir 3 S — — H H (102) Ir 3 S — — OC₂H₅ H (103) Ir 3 T H —H Br (104) Ir 3 T C₂H₅ — H H (105) Ir 3 U — — H H (106) Ir 3 U — — HC₇F₁₅ (107) Ir 3 V H — H H (108) Ir 3 W — — OCH₂C≡CCH₃ H (109) Ir 3 XCH₃ — H H (110) Ir 3 Z — H O(CH₂)₂CH(CH₃)₂ H (111) Ir 3 Z — C₃H₇ H H(112) Ir 3 A′ H H H H (113) Ir 3 B′ H — H NO₂ (114) Ir 3 B′ CH₃ — H H(115) Ir 3 C′ H C₉H₁₉ OCH₃ H (116) Pt 2 A — — H H (117) Pt 2 B H — H H(118) Pt 2 B H — H C₄F₉ (119) Pt 2 B CH₃ — OCH₃ H (120) Pt 2 B C₃H₇ — HCF₃

[0116] TABLE 13 No M n Y R₁ R₂ X₁ X₂ (121) Pt 2 B C₈H₁₇ — H H (122) Pt 2C H H H H (123) Pt 2 C H H H CF₃ (124) Pt 2 C CH₃ CH₃ H H (125) Pt 2 CC₂H₅ H H H (126) Pt 2 C C₁₀H₂₁ H OCH₃ H (127) Pt 2 D — — H H (128) Pt 2E H — H H (129) Pt 2 E CH₃ — H H (130) Pt 2 E CH₃ — H H (131) Pt 2 E CH₃— H NO₂ (132) Pt 2 E C₆H₁₃ — OC₂H₅ H (133) Pt 2 F CH₃ — H H (134) Pt 2 FC₂H₅ — H CF₃ (135) Pt 2 G H — H H (136) Pt 2 G H — H Si(CH₃)₃ (137) Pt 2G C₄H₉ — H (138) Pt 2 H H C₆H₁₃ H H (139) Pt 2 I H H H H (140) Pt 2 IC₂H₅ H H Si(C₂H₅)₃ (141) Pt 2 J — H H H (142) Pt 2 K C₅H₁₁ — H H (143)Pt 2 L C₇H₁₇ H SC₂H₅ H (144) Pt 2 N — H H H (145) Pt 2 O H — H H (146)Pt 2 P H — H H (147) Pt 2 Q H — H CH₃ (148) Pt 2 R — — H H (149) Pt 2 U— — H H (150) Pt 2 V H — NO₂ H

[0117] TABLE 14 No M n Y R₁ R₂ X₁ X₂ (151) Pt 2 W — — H H (152) Pt 2 XCH₃ — H H (153) Pt 2 Z — H H H (154) Pt 2  A′ H H H H (155) Pt 2  B′ H —OCH₃ H (156) Pt 2  C′ H H H CF₃ (157) Rh 3 B H — H Br (158) Rh 3 B H —OC₆H₁₃ H (159) Rh 3 B CH₃ — H H (160) Rh 3 C H H H H (161) Rh 3 C H HOCH₃ H (162) Rh 3 C H H NO₂ H (163) Rh 3 C H CH₃ H H (164) Rh 3 C C₆H₁₃H H Si(CH₃)₃ (165) Rh 3 D — — H H (166) Rh 3 E H — COOC₂H₅ H (167) Rh 3E CH₃ — H H (168) Rh 3 E CH₃ — H O(CH₂)₆C₂F₅ (169) Rh 3 E C₃H₇ — H H(170) Rh 3 E C₁₀H₂₁ — H H (171) Rh 3 F C₈H₁₇ — H H (172) Rh 3 G H —OCH₂CH═CH₂ H (173) Rh 3 G CH₃ — H CF₃ (174) Rh 3 H H H H H (175) Rh 3 IH H H H (176) Rh 3 K C₂H₅ — Cl H (177) Rh 3 M H H H H (178) Rh 3 N — H HH (179) Rh 3 P CH₃ — H NO₂ (180) Rh 3 S — — H H

[0118] TABLE 15 No M n Y R₁ R₂ X₁ X₂ (181) Rh 3 V H — H H (182) Rh 3 X H— SC₅H₁₁ H (183) Rh 3  C′ H OC₇H₁₅ H (184) Pd 2 B C₆H₁₃ — H H (185) Pd 2C H H OCH₃ H (186) Pd 2 C H H H H (187) Pd 2 D — — H H (188) Pd 2 E H —H CF₃ (189) Pd 2 E CH₃ — H H (190) Pd 2 F C₃H₇ — H H (191) Pd 2 G H — HH (192) Pd 2 G H — Si(CH₃)₃ H (193) Pd 2 I CH₃ H NO₂ H (194) Pd 2 J — HH H (195) Pd 2 L H H H H (196) Pd 2 M H H C₄F₉ H (197) Pd 2 O H — H C₄H₉(198) Pd 2 T H — H H (199) Pd 2 W — — OCH₃ OCH₃ (200) Pd 2  A′ CH₃ H HCl

[0119] Hereinbelow, the present invention will be described morespecifically based on Examples with reference to the drawing.

EXAMPLES I-1-I-10

[0120] In these examples, metal coordination compounds of formula (1)(Ex. Comp. Nos. (I-4), (I-7), (I-17), (I-18), (I-21), (I-23), (I-32),(I-56), (I-67) and (I-74) were used in respective luminescence layersfor Examples I-1-I-10, respectively.

[0121] Each of luminescence devices having a structure shown in FIG. 1Bwere prepared in the following manner.

[0122] On a glass substrate (transparent substrate 15), a 100 nm-thickfilm (transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

[0123] On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

[0124] Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

[0125] Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP:metal coordination compound of formula (1) (95:5 by weight)

[0126] Organic layer 3 (electron transport layer 16) (30 nm): Alq3

[0127] Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

[0128] Metal electrode layer 2 (metal electrode 11) (100 nm): Al

[0129] Each of the thus-prepared luminescence devices was taken out ofthe vacuum chamber and was subjected to a continuous energization testin an atmosphere of dry nitrogen gas stream so as to remove devicedeterioration factors, such as oxygen and moisture (water content).

[0130] The continuous energization test was performed by continuouslyapplying a voltage at a constant current density of 70 mA/cm² to theluminescence device having the ITO (transparent) electrode (as an anode)and the Al (metal) electrode (as a cathode), followed by measurement ofluminance (brightness) with time so as to determine a time (luminancehalf-life) required for decreasing an initial luminance (70-120 cd/m²)to ½ thereof.

[0131] The results are shown in Table 16 appearing hereinafter.

COMPARATIVE EXAMPLE I-1

[0132] A comparative luminescence device was prepared and evaluated inthe same manner as in Example I-1 - I-10 except that the metalcoordination compound of formula (1) was changed to Ir-phenylpyrimidinecomplex (Ir(ppy)₃) shown below.

[0133] The results are shown in Table 16 below. TABLE 16 Luminance Ex.No. Ex. Comp. No. half-life (Hr) I-1 (I-4)  750 I-2 (I-7)  500 I-3(I-17) 900 I-4 (I-18) 850 I-5 (I-21) 850 I-6 (I-23) 500 I-7 (I-32) 600I-8 (I-56) 700 I-9 (I-67) 400  I-10 (I-74) 450 Comp Ex. Ir(ppy)₃ 350 I-1

[0134] As is apparent from Table 16, compared with the conventionalluminescence device using Ir(ppy)₃, the luminescence devices using themetal coordination compounds of formula (1) according to the presentinvention provide longer luminance half-lifes, thus resulting in an ELdevice having a high durability (luminance stability) based on a goodstability of the metal coordination compound of formula (1) of thepresent invention.

EXAMPLES I-11-I-13

[0135] In these examples, metal coordination compounds of formula (1)(Ex. Comp. Nos. (I-1), (I-32) and (I-49) were used in respectiveluminescence layers for Examples I-11-I-13, respectively.

[0136] Each of luminescence devices having a structure shown in FIG. 1Cwere prepared in the following manner.

[0137] On a glass substrate (transparent substrate 15), a 100 nm-thickfilm (transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

[0138] On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

[0139] Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

[0140] Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP:metal coordination compound of formula (1) (93:7 by weight)

[0141] Organic layer 3 (exciton diffusion prevention layer 17) (10 nm):BCP

[0142] Organic layer 4 (electron transport layer 16) (30 nm): Alq3

[0143] Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

[0144] Metal electrode layer 2 (metal electrode 11) (100 nm): Al

[0145] Separately, each of the metal coordination compounds of formula(1) (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) for the thus-preparedluminescence devices was subjected to measurement of photoluminescencespectrum in order to evaluate a luminescent characteristic of the metalcoordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and(I-49)). Specifically, each of the metal coordination compounds wasdissolved in toluene at a concentration of 10⁻⁴ mol/l and subjected tomeasurement of photo-luminescence spectrum at 25° C. by using excitedlight (ca. 350 nm) and a spectrophoto-fluorometer (“Model F4500”, mfd.by Hitachi K.K.).

[0146] The results are shown in Table 17 appearing hereinafter.

[0147] The values of photoluminescence spectrum of the metalcoordination compounds (Ex. Comp. Nos. (I-1), (I-32) and (I-49)) weresubstantially equivalent to those in the luminescence devices undervoltage application as shown in Table 17, whereby it was confirmed thatluminescence caused by the luminescence device was based on luminescenceof the metal coordination compound used.

[0148] EL characteristics of the luminescence devices using the metalcoordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and(I-49)) were measured by using a microammeter (“Model 4140B”, mfd. byHewlett-Packard Co.) for a current density under application of avoltage of 12 volts (current-voltage characteristic), using aspectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peakemission wavelength λ_(PE) (luminescence spectrum), and using aluminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescenceefficiency (luminescence luminance). Further, an energy conversionefficiency was obtained according to the following equation:

[0149] Energy conversion efficiency (lm/W)

[0150] =(π×luminescence efficiency

[0151] (cd/A))/applied voltage (V).

[0152] All the above-prepared luminescence devices showed a goodrectification characteristic.

[0153] The results are shown in Table 17.

COMPARATIVE EXAMPLE I-2

[0154] A comparative luminescence device was prepared and evaluated inthe same manner as in Example I-2 - I-13 except that the metalcoordination compound of formula (1) was changed to Ir-phenylpyrimidinecomplex (Ir(ppy)₃) shown below.

[0155] The results are shown in Table 17 below. TABLE 17 Energy Ex. λPEin conversion Luminescence Comp. toluene λPE efficiency efficiencyCurrent density Luminance Ex. No No. (nm) (nm) (Im/W) (cd/A) (mA/cm² at12 V) half-life (Hr) I-11 (I-1) 522 525 4.0 13.6 170 300 I-12 (I-32) 487525 0.4 2.4 130 400 I-13 (I-49) 537 545 2.1 7.0  25 250 Comp. Ir(ppy)₃510 510 6.0 19.0  20 150 Ex. I-2

[0156] As shown in Table 17, compared with the luminescence device usingIr(ppy)₃ (Comparative Example I-2) showing λ_(PE=)510 nm, theluminescence devices using the metal coordination compound of formula(1) according to the present invention showed longer peak emissionwavelengths (λ_(PE)=525-545 nm) by 15-35 nm, thus resulting in smallerrelative luminous efficiencies.

[0157] Smaller energy conversion efficiencies (0.4-4.0 lm/W) andluminescence efficiencies (2.4-13.6 cd/A) of the luminescence devices ofthe present invention compared with those (6.0 lm/W and 19.0 cd/A) ofthe luminescence device using Ir(ppy)₃ may be attributable to thesmaller relative luminous efficiencies due to the longer peak emissionwavelengths, thus not resulting in essentially inferior luminescentcharacteristics of the luminescence devices using the metal coordinationcompound of formula (1) of the present invention.

[0158] As apparent from the results of the luminance half-lifes of theluminescence devices, compared with the luminescence device usingIr(ppy)₃ showing the luminance half-life of 150 hours, the luminescencedevices using the metal coordination compounds of formula (1) accordingto the present invention showed considerably longer luminance half-lifesof 250-400 hours.

EXAMPLE I-14 (Synthesis of Ex. Comp. No. (I-1))

[0159]

[0160] In a 1 liter-three necked flask, 20.0 g (126.6 mM) of2-bromopyridine, 17.7 g (126.4 mM) of 3-fluorophenylbronic acid, 130 mlof toluene, 65 ml of ethanol and 130 ml of 2M-sodium carbonate aqueoussolution were placed and stirred in a nitrogen gas stream at roomtemperature. Under stirring, to the mixture, 4.60 g (3.98 mM) oftetrakis (triphenyl-phosphine) palladium (0) was added, followed byheat-refluxing for 6 hours under stirring in nitrogen gas stream.

[0161] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue. The residuewas purified by silica gel column chromatography (eluent: toluene/ethylacetate=5/1) to obtain 6.0 g of 2-(3-fluorophenyl)pyridine (pale brownliquid) (Yield: 34.6%).

[0162] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140{square root} C. while supplyingnitrogen gas therein in the form of bubbles, followed by cooing to 100°C. by standing. To glycerol, 1.04 g (6.00 mM) of2-(3-fluorophenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III)acetylacetonate were added, followed by heat-refluxing for 10 hoursunder stirring in nitrogen gas stream.

[0163] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 300 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 5 hours at 100° C. under reduced pressure and purification by silicagel column chromatography (eluent: chloroform) to obtain 0.22 g ofIridium (III) tris[2-(3-fluorophenyl)pyridine] (yellow powder) (Yield:31.0%).

EXAMPLE I-15 (Synthesis of Ex. Comp. No. (I-32))

[0164]

[0165] In a 1 liter-three necked flask, 20.8 g (131.6 mM) of2-bromopyridine, 25.0 g (131.6 mM) of 3-trifluoromethylphenylbronicacid, 130 ml of toluene, 65 ml of ethanol and 130 ml of 2M-sodiumcarbonate aqueous solution were placed and stirred in a nitrogen gasstream at room temperature. Under stirring, to the mixture, 4.76 g (4.12mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followedby heat-refluxing for 7 hours under stirring in nitrogen gas stream.

[0166] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue (pale brownliquid). The residue was purified by silica gel column chromatography(eluent: toluene/hexane=1/1) to obtain 6.0 g of2-(3-trifluoromethylphenyl)pyridine (pale brown liquid) (Yield: 21.1%).

[0167] In a 200 ml-four necked flask, 100 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 2.68 g (12.0 mM) of2-(3-trifluoromethylphenyl)pyridine and 1.00 g (2.04 mM) of Iridium(III) acetylacetonate were added, followed by heat-refluxing for 10hours under stirring in nitrogen gas stream.

[0168] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 600 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 5 hours at 100°°C. under reduced pressure. The precipitate wasdissolved in chloroform and the insoluble matter was removed byfiltration, followed by purification by silica gel column chromatography(eluent: chloroform) and recyrstallization from a mixture solvent(chloroform/methanol) to obtain 0.62 g of Iridium (III)tris[2-(3-trifluoromethylphenyl)-pyridine] (yellow powder) (Yield:35.3%), which showed a peak emission wavelength λ_(PE) in toluene at 25°C. of 487 nm.

EXAMPLE I-16 (Synthesis of Ex. Comp. No. (I-49))

[0169]

[0170] In a 1 liter-three necked flask, 25.6 g (141.0 mM) of2-chloro-5-trifluoromethylpyridine, 17.2 g (141.0 mM) of phenylbronicacid, 140 ml of toluene, 70 ml of ethanol and 140 ml of 2M-sodiumcarbonate aqueous solution were placed and stirred in a nitrogen gasstream at room temperature. Under stirring, to the mixture, 5.10 g (4.41mM) of tetrakis (triphenyl-phosphine) palladium (0) was added, followedby heat-refluxing for 6 hours under stirring in nitrogen gas stream.

[0171] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene. The organic layer was washedwith water until the system showed neutral, followed by distilling offof the solvent under reduced pressure to obtain a residue. The residuewas purified by silica gel column chromatography (eluent:toluene/hexane=5/1). The resultant creamy crystal was purified byalumina column chromatography (eluent: toluene) and recrystallized fromethanol to obtain 13.1 g of 2-phenyl-5-trifluoromethylpyridine(colorless crystal) (Yield: 41.6%).

[0172] In a 200 ml-four necked flask, 100 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 2.68 g (12.0 mM) of2-phenyl-5-trifluoromethylpyridine and 1.00 g (2.04 mM) of Iridium (III)acetylacetonate were added, followed by heat-refluxing for 8 hours understirring in nitrogen gas stream.

[0173] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 600 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 4 hours at 100° C. under reduced pressure and purification by silicagel column chromatography (eluent: chloroform) to obtain 0.43 g ofIridium (III) tris-(2-phenyl-5-trifluoromethylpyridine) (orange powder)(Yield: 24.5%).

EXAMPLE I-17 (Synthesis of Ex. Comp. No. (I-122))

[0174]

[0175] In a 100 ml-three necked flask, 3.16 g (19.9 mM) of2-bromopyridine, 3.16 g (20.0 mM) of 2,4-difluorophenylbronic acid, 15ml of toluene, 7.5 ml of ethanol and 15 ml of 2M-sodium carbonateaqueous solution were placed and stirred in a nitrogen gas stream atroom temperature. Under stirring, to the mixture, 0.72 g (0.62 mM) oftetrakis (triphenyl-phosphine) palladium (0) was added, followed byheat-refluxing for 8 hours and 40 minutes under stirring in nitrogen gasstream.

[0176] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and ethyl acetate. The organic layer waswashed with water followed by distilling off of the solvent underreduced pressure to obtain a residue. The residue was purified by silicagel column chromatography (eluent: toluene/ethyl acetate=10/1) to obtain3.28 g of 2-(2,4-difluorophenyl)pyridine (pale yellow oily product)(Yield: 86.0%).

[0177] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 0.96 g (5.02 mM) of2-(2,4-difluorophenyl)pyridine and 0.50 g (1.02 mM) of Iridium (III)acetylacetonate were added, followed by heat-refluxing for 10 hoursunder stirring in nitrogen gas stream.

[0178] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 300 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 5 hours at 100° C. under reduced pressure and purification by silicagel column chromatography (eluent: chloroform) and recrystallizationfrom a mixture solvent (chloroform/methanol) to obtain 0.25 g of Iridium(III) tris[2-(4,6-difluorophenyl)-pyridine] (yellow powder) (Yield:32.1%), which showed a peak emission wavelength λ_(PE) in toluene at 25°C. of 471 nm.

EXAMPLE I-18 (Synthesis of Ex. Comp. No. (I-121))

[0179]

[0180] In a 500 ml-three necked flask, 11.0 g (45.3 mM) of5-bromo-2-fluorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF)were placed and stirred in a nitrogen gas stream at room temperature.Under stirring, to the mixture, 2.60 g (2.25 mM) oftetrakis(triphenylphosphine) palladium (0) was added, followed bycooling to 20-21° C. (inner temperature) on an ice bath in nitrogen gasstream. At that temperature, 90 ml of 0.5 M-THF solution of2-pyridylzinc bromide was gradually added dropwise to the mixture innitrogen gas stream, followed by stirring for 4 hours at thattemperature.

[0181] After the reaction, the reaction mixture was poured into coolwater, followed by addition of ethyl acetate to remove the insolublematter by filtration. The organic layer was washed with water and driedwith anhydrous sodium sulfate, followed by distilling-off of the solventunder reduced pressure to obtain a residue.

[0182] The residue was purified by silica gel column chromatography(eluent: hexane/ethyl acetate=20/1) to obtain 1.80 g of2-(4-fluoro-3-trifluoromethyl-phenyl)pyridine (pale brown oily product)(Yield: 16.6%)

[0183] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100°°C. bystanding. To glycerol, 1.21 g (5.02 mM) of2-(4-fluoro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for10 hours under stirring in nitrogen gas stream.

[0184] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 300 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 5 hours at 100° C. under reduced pressure and purification by silicagel column chromatography (eluent: chloroform) and recrystallizationfrom a mixture solvent (chloroform/methanol) to obtain 0.20 g of Iridium(III) tris[2-(4-fluoro-5-trifluoromethyl-phenyl)pyridine] (yellowpowder) (Yield: 21.5%), which showed a peak emission wavelength λ_(PE)in toluene at 25° C. of 466 nm.

EXAMPLE I-19 (Synthesis of Ex. Comp. No. (I-111))

[0185]

[0186] In a 500 ml-three necked flask, 11.8 g (45.5 mM) of5-bromo-2-chlorobenzotrifluoride and 90 ml of dry tetrahydrofuran (THF)were placed and stirred in a nitrogen gas stream at room temperature.Under stirring, to the mixture, 2.60 g (2.25 mM) oftetrakis(triphenylphosphine) palladium (0) was added, followed bycooling to 13.5-14° C. (inner temperature) on an ice bath in nitrogengas stream. At that temperature, 90 ml of 0.5 M-THF solution of2-pyridylzinc bromide was gradually added dropwise to the mixture innitrogen gas stream, followed by stirring for 3 hours at ca. 20° C.

[0187] After the reaction, the reaction mixture was poured into coolwater, followed by addition of ethyl acetate to remove the insolublematter by filtration. The organic layer was washed with water and driedwith anhydrous sodium sulfate, followed by distilling-off of the solventunder reduced pressure to obtain a residue. The residue was purified bysilica gel column chromatography (eluent: hexane/ethyl acetate=10/1) toobtain 3.70 g of 2-(4-chloro-5-trifluoro-methylphenyl)pyridine (palebrown oily product) (Yield: 31.9%).

[0188] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.29 g (5.01 mM) of2-(4-chloro-3-trifluoromethylphenyl)pyridine and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for8 hours under stirring in nitrogen gas stream.

[0189] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 300 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by dryingfor 5 hours at 100° C. under reduced pressure and purification by silicagel column chromatography (eluent: chloroform) and recrystallizationfrom a mixture solvent (chloroform/hexane) to obtain 0.25 g of Iridium(III) tris[2-(4-chloro-3-trifluoromethylphenyl)pyridine] (yellow powder)(Yield: 25.4%), which showed a peak emission wavelength λ_(PE) intoluene at 25° C. of 479 nm.

COMPARATIVE EXAMPLE I-3 (Synthesis of metal coordination compound A)

[0190] A metal coordination compound A (iridium (III)tris[2-(4,5-difluoromethylphenyl)pyridine described in PolymerPreprints, 41(1), pp. 770-771 (2000)) was prepared in the same manner asin Example 17 except that 2,4-difluorophenylbronic acid was changed to3,4-difluorophenylbronic acid.

[0191] The metal coordination compound A showed a peak emissionwavelength λ_(PE) in toluene at 25° C. of 505 nm.

EXAMPLE I-20 AND COMPARATIVE EXAMPLE I-4

[0192] Two luminescence devices were prepared and evaluated in the samemanner as in Examples I-1 to I-10 except that the metal coordinationcompound was changed to one (Ex. Comp. No. (122)) prepared in Example1-18 (for Example I-20) and the metal coordination compound A preparedin Comparative Example 3 (for Comparative Example 4), respectively.

[0193] The results are shown in Table 18 below. TABLE 18 Luminance Ex.No. Ex. Comp. No. half-life (Hr)  I-20 (I-122) 630 Comp. Ex. Metal 310I-4 coordination compound A

[0194] As apparent from Table 18, the luminescence device using themetal coordination compound of formula (1) according to the presentinvention exhibited a luminance half-life considerably longer than thatof the luminescence device using the metal coordination compound A, thusresulting in an EL device excellent in durability (luminance stability).

[0195] As described hereinabove, the metal coordination compound offormula (1) according to the present invention provides a higherphosphorescence efficiency and a shorter phosphorescence life and allowscontrol of its emission wavelength by appropriately modifying thesubstituents X1 to X8, thus being suitable as a luminescent material forEL device.

[0196] The result EL device (luminescence device) having an organiclayer containing the metal coordination compound of formula (1) exhibitsexcellent characteristics including a high efficiency luminescence, ahigh luminance for a long period, and a decreased luminescencedeterioration in energized state.

EXAMPLES II-1-II-15

[0197] In these examples, metal coordination compounds of formula (1)(Ex. Comp. Nos. (II-10), (II-15), (II-17), (II-21), (II-39), (II-43),(II-46), (II-85), (II-96), (II-122), (II-131), (II-146), (II-163),(II-177) and (II-182) were used in respective luminescence layers forExamples II-1-II-15, respectively.

[0198] Each of luminescence devices having a structure shown in FIG. 1Bwere prepared in the following manner.

[0199] On a glass substrate (transparent substrate 15), a 100 nm-thickfilm (transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

[0200] On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

[0201] Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

[0202] Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP:metal coordination compound of formula (2) (95:5 by weight)

[0203] Organic layer 3 (electron transport layer 16) (30 nm): Alq3

[0204] Metal electrode layer 1 (metal electrode 11) (15 nm): Al—Li alloy(Li=1.8 wt. %)

[0205] Metal electrode layer 2 (metal electrode 11) (100 nm): Al

[0206] Each of the thus-prepared luminescence devices was taken out ofthe vacuum chamber and was subjected to a continuous energization testin an atmosphere of dry nitrogen gas stream so as to remove devicedeterioration factors, such as oxygen and moisture (water content).

[0207] The continuous energization test was performed by continuouslyapplying a voltage at a constant current density of 70 mA/cm² to theluminescence device having the ITO (transparent) electrode (as an anode)and the Al (metal) electrode (as a cathode), followed by measurement ofluminance (brightness) with time so as to determine a time (luminancehalf-life) required for decreasing an initial luminance (60-220 cd/m²)to ½ thereof.

[0208] The results are shown in Table 19 appearing hereinafter.

COMPARATIVE EXAMPLE II-1

[0209] A comparative luminescence device was prepared and evaluated inthe same manner as in Example II-1-II-15 except that the metalcoordination compound of formula (2) was changed to Ir-phenylpyrimidinecomplex (Ir(ppy)₃) shown below.

[0210] The results are shown in Table 19 below. TABLE 19 Luminance Ex.No. Ex. Comp. No. half-life (Hr) II-1 (II-10) 750 II-2 (II-15) 950 II-3(II-17) 800 II-4 (II-21) 850 II-5 (II-39) 900 II-6 (II-43) 750 II-7(II-46) 900 II-8 (II-85) 500 II-9 (II-96) 650  II-10  (II-122) 650 II-11  (II-131) 600  II-12  (II-146) 550  II-13  (II-163) 600  II-14 (II-177) 450  II-15  (II-182) 450 Comp. Ex. Ir(ppy)₃ 350 II-1

[0211] As is apparent from Table 19, compared with the conventionalluminescence device using Ir(ppy)₃, the luminescence devices using themetal coordination compounds of formula (2) according to the presentinvention provide longer luminance half-lifes, thus resulting in an ELdevice having a high durability (luminance stability) based on a goodstability of the metal coordination compound of formula (2) of thepresent invention.

EXAMPLES II-16-II-17

[0212] In these examples, metal coordination compounds of formula (2)(Ex. Comp. Nos. II-15 and II-17 were used in respective luminescencelayers for Examples II-16-II-17, respectively.

[0213] Each of luminescence devices having a structure shown in FIG. 1Cwere prepared in the following manner.

[0214] On a glass substrate (transparent substrate 15), a 100 nm-thickfilm (transparent electrode 14) of ITO (indium tin oxide) was formed bysputtering, followed by patterning to have an (opposing) electrode areaof 3 mm².

[0215] On the ITO-formed substrate, three organic layers and two metalelectrode layers shown below were successively formed by vacuum (vapor)deposition using resistance heating in a vacuum chamber (10⁻⁴ Pa).

[0216] Organic layer 1 (hole transport layer 13) (40 nm): α-NPD

[0217] Organic layer 2 (luminescence layer 12) (20 nm): mixture of CBP:metal coordination compound of formula (2) (93:7 by weight)

[0218] Organic layer 3 (exciton diffusion prevention layer 17) (10 nm):BCP

[0219] Organic layer 4 (electron transport layer 16) (30 nm): Alq3

[0220] Metal electrode layer 1 (metal electrode 11) (15 nm): Al-Li alloy(Li=1.8 wt. %)

[0221] Metal electrode layer 2 (metal electrode 11) (100 nm): Al

[0222] Separately, each of the metal coordination compounds of formula(2) (Ex. Comp. Nos. (II-15 and (II-17))) for the thus-preparedluminescence devices was subjected to measurement of photoluminescencespectrum in order to evaluate a luminescent characteristic of the metalcoordination compounds of formula (2) (Ex. Comp. Nos. (II-15) and(II-17)). Specifically, each of the metal coordination compounds wasdissolved in toluene at a concentration of 10⁻⁴ mol/l and subjected tomeasurement of photo-luminescence spectrum at 25° C. by using excitedlight (ca. 350 nm) and a spectrophoto-fluorometer (“Model F4500”, mfd.by Hitachi K.K.).

[0223] The results are shown in Table 20 appearing hereinafter.

[0224] The values of photoluminescence spectrum of the metalcoordination compounds (Ex. Comp. Nos. (II-15) and (II-17)) weresubstantially equivalent to those in the luminescence devices undervoltage application as shown in Table 20, whereby it was confirmed thatluminescence caused by the luminescence device was based on luminescenceof the metal coordination compound used.

[0225] EL characteristics of the luminescence devices using the metalcoordination compounds of formula (1) (Ex. Comp. Nos. (I-1), (I-32) and(I-49)) were measured by using a microammeter (“Model 4140B”, mfd. byHewlett-Packard Co.) for a current density under application of avoltage of 12 volts (current-voltage characteristic), using aspectrophotofluoro-meter (“Model SR1”, mfd. by Topcon K.K.) for a peakemission wavelength λ_(PE) (luminescence spectrum), and using aluminance meter (“Model BM7”, mfd. by Topcon K.K.) for a luminescenceefficiency (luminescence luminance). Further, an energy conversionefficiency was obtained according to the following equation:

[0226] Energy conversion efficiency (lm/W)

[0227] =(π×luminescence efficiency

[0228] (cd/A))/applied voltage (V).

[0229] All the above-prepared luminescence devices showed a goodrectification characteristic.

[0230] The results are shown in Table 20.

COMPARATIVE EXAMPLE II-2

[0231] A comparative luminescence device was prepared and evaluated inthe same manner as in Example II-16-II-17 except that the metalcoordination compound of formula (1) was changed to Ir-phenylpyrimidinecomplex (Ir(ppy)₃) shown below.

[0232] The results ate shown in Table 20 below. TABLE 20 Energy Ex. λPEin conversion Luminescence Comp. toluene λPE efficiency efficiencyCurrent density Luminance Ex. No No. (nm) (nm) (Im/W) (cd/A) (mA/cm² at12 V) half-life (Hr) II-16 (II-15) 524 565 0.9 7.5 70 250 II-17 (II-17)554 565 3.4 9.6 180  300 Comp. Ir(ppy)₃ 510 510 6.0 19.0  20 150 Ex.II-2

[0233] As shown in Table 20, compared with the luminescence device usingIr(ppy)₃ (Comparative Example II-2) showing λ_(PE)=510 nm, theluminescence devices using the metal coordination compound of formula(2) according to the present invention showed longer peak emissionwavelengths (λ_(PE) =565 nm) by 55 nm, thus resulting in smallerrelative luminous efficiencies.

[0234] Smaller energy conversion efficiencies (0.9 -3.4 lm/W) andluminescence efficiencies (7.5-9.6 cd/A) of the luminescence devices ofthe present invention compared with those (6.0 lm/W and 19.0 cd/A) ofthe luminescence device using Ir(ppy)₃ may be attributable to thesmaller relative luminous efficiencies due to the longer peak emissionwavelengths, thus not resulting in essentially inferior luminescentcharacteristics of the luminescence devices using the metal coordinationcompound of formula (2) of the present invention.

[0235] As apparent from the results of the luminance half-lifes of theluminescence devices, compared with the luminescence device usingIr(ppy)₃ showing the luminance half-life of 150 hours, the luminescencedevices using the metal coordination compounds of formula (2) accordingto the present invention showed considerably longer luminance half-lifesof 250-300 hours.

EXAMPLE II-18 (Synthesis of Ex. Comp. No. (II-15))

[0236]

[0237] In a 5 liter-three necked flask, 169.5 g (1.28 M) of1,2,3,4-tetrahydronaphthalene and 3 liters of acetic acid were placedand stirred at room temperature. Under stirring, to the mixture, 650 g(1.67 M) of benzyltrimethylammonium bromide and 244.8 g (1.80 M) of zincchloride were successively added, followed by stirring for 5.5 hours at70° C. After the reaction, the reaction mixture was cooled to roomtemperature and poured into 3 liters of ice water, followed byextraction with methyl t-butyl ether. The organic layer was successivelywashed with 5%-NaHSO₃ aqueous solution, 5%-NaOH aqueous solution anddistilled water, followed by distilling-off of the solvent under reducedpressure to obtain 243.2 g of a dark brown liquid. The liquid wassubjected to vacuum distillation (distillation under reduced pressure)(boiling point=108-110° C. at 667 Pa) to obtain 130.2 g of6-bromo-1,2,3,4-tetrahydronaphthalene (Yield: 48.1%).

[0238] In a 5 liter-three necked flask, 67.55 g of6-bromo-1,2,3,4-tetrahydronaphthalene and 1480 ml of dry tetrahydrofuran(THF) were placed and cooled to −70 to −68° C. on a dry ice-acetone bathin a dry nitrogen gas atmosphere. At that temperature, to the mixture,200 ml of 1.6 M-butyllithium solution in hexane was added dropwise,followed by stirring for 2 hours at −67° C. or below. To borate in 435ml of dry THF was added dropwise at −70°to −68° C., followed by stirringfor 2 hours at −67° C. or below. The reaction mixture was graduallywarmed to room temperature and left standing overnight. The resultantreaction mixture was gradually added dropwise to a mixture of 108 ml ofHCl and 438 ml of water kept at 10° C. or below, followed by stirringfor 1 hour at that temperature. Thereafter, the mixture was subjected toextraction with toluene. The organic layer was washed with water,followed by distilling-off of the solvent under reduced pressure toobtain a residue. The residue was purified by silica gel columnchromatography (eluent: toluene/ethyl acetate=2/1) and recrystallizedfrom hexane to obtain 30.4 g of 1,2,3,4-tetrahydronaphthalene-6-boronicacid (Yield: 54.0%).

[0239] In a 1 liter-three necked flask, 17.8 g (114 mM) of2-bromopyridine, 20.0 g (127 mM) of1,2,3,4-tetrahydronaphthalene-6-bronic acid, 160 ml of toluene, 80 ml ofethanol and 160 ml of 2M-sodium carbonate aqueous solution were placedand stirred in a nitrogen gas stream at room temperature. Understirring, to the mixture, 4.05 g (3.5 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 7 hours under stirring in nitrogen gas stream.

[0240] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene, and distilling off of thesolvent under reduced pressure to obtain a residue. The residue waspurified by silica gel column chromatography (eluent:toluene/hexane=2/1) to obtain 9.2 g of6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene (yellow liquid) (Yield:38.6%).

[0241] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.30 g (6.21 mM) of6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and 0.50 g (1.02 mM) ofIridium (III) acetylacetonate were added, followed by heat-refluxing for5 hours under stirring in nitrogen gas stream.

[0242] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 100 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by washingwith acetone and purification by silica gel column chromatography(eluent: chloroform) to obtain 0.14 g of Iridium (III)tris[6-(pyridine-2-yl)-1,2,3,4-tetrahydronaphthalene] (orange powder)(Yield: 16.8%).

EXAMPLE II-19 (Synthesis of Ex. Comp. No. (II-17))

[0243]

[0244] In a 200 ml-four necked flask, 5.16 g (28.4 mM) of2-chloro-5-trifluoromethyl, 5.00 g (28.4 mM) of1,2,3,4-tetrahydronaphthalene-6-bronic acid, 25 ml of toluene, 12.5 mlof ethanol and 25 ml of 2M-sodium carbonate aqueous solution were placedand stirred in a nitrogen gas stream at room temperature. Understirring, to the mixture, 1.02 g (0.88 mM) of tetrakis(triphenylphosphine) palladium (0) was added, followed by heat-refluxingfor 3.25 hours under stirring in nitrogen gas stream.

[0245] After the reaction, the reaction mixture was cooled, followed byextraction with cool water and toluene, and distilling off of thesolvent under reduced pressure to obtain a residue. The residue waspurified by silica gel column chromatography (eluent:toluene/hexane=1/1) and alumina column chromatography (eluent: toluene)and recrystallized from methanol to obtain 3.14 g of6-(5-trifluoro-methylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene(colorless crystal) (Yield: 39.9%).

[0246] In a 100 ml-four necked flask, 50 ml of glycerol was placed andheat-stirred for 2 hours at 130-140° C. while supplying nitrogen gastherein in the form of bubbles, followed by cooing to 100° C. bystanding. To glycerol, 1.72 g (6.20 mM) of6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene and0.50 g (1.02 mM) of Iridium (III) acetylacetonate were added, followedby heat-refluxing for 7 hours under stirring in nitrogen gas stream.

[0247] After the reaction, the reaction mixture was cooled to roomtemperature and poured into 100 ml of 1N-HCl. The resultant precipitatewas recovered by filtration and washed with water, followed by washingwith acetone and purification by silica gel column chromatography(eluent: chloroform) to obtain 0.11 g of Iridium (III)tris[6-(5-trifluoromethylpyridine-2-yl)-1,2,3,4-tetrahydronaphthalene](orange powder) (Yield: 10.5%).

[0248] As described hereinabove, the metal coordination compound offormula (2) according to the present invention provides a higherphosphorescence efficiency and a shorter phosphorescence life and allowscontrol of its emission wavelength by appropriately modifying thealkylene group Y and/or substituents X1 and X2, thus being suitable as aluminescent material for EL device.

[0249] The result EL device (luminescence device) having an organiclayer containing the metal coordination compound of formula (2) exhibitsexcellent characteristics including a high efficiency luminescence, ahigh luminance for a long period, and a decreased luminescencedeterioration in energized state.

What is claimed is:
 1. A luminescence device, comprising: an organiccompound layer comprising a metal coordination compound represented bythe following formula (1):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independentlydenote hydrogen atom or a substituent selected from the group consistingof halogen atom; nitro group; trifluoromethyl group trialkylsilyl grouphaving three linear or branched alkyl groups each independently having1-8 carbon atoms; and a linear or branched alkyl group having 2-20carbon atoms capable of including one or at least two non-neighboringmethylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—,—O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom whichcan be replaced with fluorine atom; with the proviso that at least oneof X1 to X8 is a substituent other than hydrogen atom, and X2 and X3cannot be fluorine atom at the same time.
 2. A device according to claim1, wherein at least two of X1 to X8 are substituents other than hydrogenatom.
 3. A device according to claim 1, wherein at least one of X5 to X8is a substituent other than hydrogen atom.
 4. A device according toclaim 1, wherein at least two of X1 to X4 are substituents other thanhydrogen atom.
 5. A device according to claim 1, wherein at least one ofX2, X3 and X4 has a Hammett's substituent constant of at least 0.2 withrespect to the carbon atom connected to M, and the metal coordinationcompound exhibits a peak emission wavelength in toluene at 25° C. of atmost 490 nm.
 6. A device according to claim 1, wherein X2, X3 and X4provides a sum of Hammett's substituent constant of at least 0.41 withrespect to the carbon atom connected to M, and the metal coordinationcompound exhibits a peak emission wavelength in toluene at 25° C. of atmost 490 nm.
 7. A device according to claim 6, wherein the sum ofHammett's substituent constant is at least 0.50.
 8. A luminescencedevice, comprising: an organic compound layer comprising a metalcoordination compound having at least one substituent, wherein said atleast one substituent includes a substituent having a Hammett'ssubstituent constant of at least 0.2, and the metal coordinationcompound exhibits a peak emission wavelength in toluene at 25° C. of atmost 490 nm.
 9. A device according to claim 8, wherein said at least onesubstituent includes two or more substituents each having a Hammett'ssubstituent constant of at least 0.2.
 10. A device according to claim 1,further comprising a pair of electrodes oppositely disposed to sandwichthe organic compound layer, wherein a voltage is applied between thepair of electrodes to cause luminescence.
 11. A display apparatus,comprising: a luminescence device according to claim 1 and drive meansfor driving the luminescence device.
 12. A metal coordination compound,adapted for use in a luminescence device, represented by the followingformula (1):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independentlydenote hydrogen atom or a substituent selected from the group consistingof halogen atom; nitro group; trifluoromethyl group trialkylsilyl grouphaving three linear or branched alkyl groups each independently having1-8 carbon atoms; and a linear or branched alkyl group having 2-20carbon atoms capable of including one or at least two non-neighboringmethylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—,—O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom whichcan be replaced with fluorine atom; with the proviso that at least oneof X1 to X8 is a substituent other than hydrogen atom, and X2 and X3cannot be fluorine atom at the same time.
 13. A compound according toclaim 12, wherein at least two of X1 to X8 are substituents other thanhydrogen atom.
 14. A compound according to claim 12, wherein at leastone of X5 to X8 is a substituent other than hydrogen atom.
 15. Acompound according to claim 12, wherein at least two of X1 to X4 aresubstituents other than hydrogen atom.
 16. A compound according to claim12, wherein at least one of X2, X3 and X4 has a Hammett's substituentconstant of at least 0.2 with respect to the carbon atom connected to M,and the metal coordination compound exhibits a peak emission wavelengthin toluene at 25° C. of at most 490 nm.
 17. A compound according toclaim 12, wherein X2, X3 and X4 provides a sum of Hammett's substituentconstant of at least 0.41 with respect to the carbon atom connected toM, and the metal coordination compound exhibits a peak emissionwavelength in toluene at 25° C. of at most 490 nm.
 18. A compoundaccording to claim 17, wherein the sum of Hammett's substituent constantis at least 0.50.
 19. A metal coordination compound having at least onesubstituent adapted for use in a luminescence device, wherein said atleast one substituent includes a substituent having a Hammett'ssubstituent constant of at least 0.2, and the metal coordinationcompound exhibits a peak emission wavelength in toluene at 25 25° C. ofat most 490 nm.
 20. A compound according to claim 19, wherein said atleast one substituent includes two or more substituents each having aHammett's substituent constant of at least 0.2.
 21. A luminescencedevice, comprising: an organic compound layer comprising a metalcoordination compound represented by the following formula (2):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene grouphaving 2-4 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S— or—CO— and capable of including hydrogen atom which can be replaced with alinear or branched alkyl group having 1-10 carbon atoms; and X1 and X2independently denote hydrogen atom; halogen atom; nitro group;trialkylsilyl group having 1-8 carbon atoms; or a linear or branchedalkyl group having 1-20 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable ofincluding hydrogen atom which can be replaced with fluorine atom.
 22. Adevice according to claim 21, wherein at least one of X1 to X2 ishydrogen atom.
 23. A device according to claim 21, further comprising apair of electrodes oppositely disposed to sandwich the organic compoundlayer, wherein a voltage is applied between the pair of electrodes tocause luminescence.
 24. A metal coordination compound, adapted for usein a luminescence device, represented by the following formula (2):

wherein M denotes Ir, Rh or Pd; n is 2 or 3; Y denotes an alkylene grouphaving 2-4 carbon atoms capable of including one or at least twonon-neighboring methylene groups which can be replaced with —O—, —S— or—CO— and capable of including hydrogen atom which can be replaced with alinear or branched alkyl group having 1-10 carbon atoms; and X1 and X2independently denote hydrogen atom; halogen atom; nitro group;trialkylsilyl group having 1-8 carbon atoms; or a linear or branchedalkyl group having 1 -20 carbon atoms capable of including one or atleast two non-neighboring methylene groups which can be replaced with—O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable ofincluding hydrogen atom which can be replaced with fluorine atom.
 25. Acompound according to claim 24, wherein at least one of X1 to X2 ishydrogen atom.